James Cohen, professor at Fordham University, assumes the subpoenas would come from the US Southern District, since that is where Goldman is headquartered, and he believes Preet Bharara, the attorney in charge of that office, is well aware of criticism of law enforcement for having made no major prosecutions of Wall Street figures in connection to the crisis.

"I think the decision to go forward with a subpoena is a signal that they think they're going to find some dirt--criminal dirt," Cohen says.

Stanley Sporkin, former head of enforcement for the Securities and Exchange Commission, sees things slightly differently. He believes Bharara is taking a methodical, responsible approach to his investigation.

"He's not just going to go out there and swing for the fences. He's going to build, single by single, a case. He's careful, but he knows, in fairness to everybody, that it's got to be a good case before he brings it."

Bringing an indictment shouldn't be difficult, says Michael Diaz, managing partner at Diaz Reus and a former assistant state attorney in Florida under Janet Reno.

Winning the case "depends on the ability of the Department of Justice to dumb it down for a jury and not get into the details of synthetic derivatives and what that all means," says Diaz, who says he has no cases pending against Goldman but is investigating a possible class action lawsuit against the company.

"They need to make the jury understand that Goldman Sachs had an opportunity to not do this, that they did this for financial reasons, that they failed to disclose information that they otherwise had available to them, that they did this strictly for the purposes of their own financial gain and they victimized the public, their own clients, investors and everyone else," Diaz says.

Lawrence Mitchell, professor at George Washington University's law school, is skeptical, however, noting the SEC's "relatively quick" $550 million settlement with Goldman last year.

"One would have thought, especially given the public statement that the SEC's initial litigation signified that they would not have settled had they thought they had a strong enough case against Goldman to win on the civil standard. That gives me some reason to doubt the ability of a federal prosecutor to win a case against Goldman except for the possibility that new evidence has emerged," Mitchell says.

Indeed, The Wall Street Journal noted in its article breaking the news of the investigation that Goldman already "turned over hundreds of millions of pages of documents to the Federal Crisis Inquiry Commission," suggesting it might be difficult to find new evidence.

However, former SEC enforcement chief Sporkin notes the FCIC wasn't pursuing a criminal investigation, and says the subpoenas can be more targeted in their search.

He also argues the SEC settlement should be seen as a victory by the regulator.

"Of course it's a victory. Are you kidding? Taking on an issue of that kind and going against the number one investment banking firm in the world and then coming out ahead after the defendant had said there was no case and they weren't going to concede? Anybody who tells you it's anything less than that-- I don't know what they're smoking."